Slice or Hook on Screen: What Your Launch Monitor Measures and What It Guesses

Yes. Any launch monitor that tracks spin axis or side spin, or that follows the ball's direction after impact, can show a slice or a hook on screen. The curve is the easy part to see. What most units can't always tell you is why the ball curved.

The why sits in two numbers: the direction the clubface points at impact, and the direction the club travels through the ball. Only devices that measure club data can report both. Ball-only units show the result of the curve, and a fix needs the cause.

This page explains those two numbers, which device types measure them and which estimate them, and how to read a miss from them. It works one numeric example and finishes with the setup errors that can turn a straight shot into a slice on screen.

How we put this together: we compared published manufacturer specs and general ball-flight physics. We have not tested these units ourselves. Links on this page may earn us a commission.

Yes, and the useful part is the reason behind the curve

A slice on screen is a result. For a right-handed golfer, the ball curves right because of the relationship between two angles at impact. A launch monitor can display that result using spin data alone, but the cause lives in the club data.

The rest of this page is an analysis of published specifications and well-established ball-flight physics. We have not tested the units mentioned here. Treat the device notes as a guide to what each class is designed to measure, and check the maker's current documentation before you buy.

Face, path and curve: the physics in two numbers

Everything below is written for a right-handed golfer. A slice curves right and a hook curves left. Left-handers see the mirror image, so their slice curves left.

Face angle is where the clubface points at impact, measured against the target line. Club path is the direction the clubhead travels through impact. A path that moves from outside the target line toward the inside is out-to-in, which is the classic slice path. A path from inside to outside is in-to-out.

Face-to-path is face angle minus club path. A positive number means the face is open relative to the path, which tilts the spin axis so the ball curves right. A negative number curves it left. A slice is a large positive gap and a fade is a small one. The mechanism is the same; only the size differs.

Start line comes mostly from the face

The starting direction of the ball follows the face more closely than the path. Many sources describe the face as the larger influence on start line, but the exact split changes with the club and the strike, so don't treat it as a fixed percentage.

That is why a pull-slice, a ball that starts left and curves right, usually means the face is left of target and also open to a path that is even further left.

Curve comes from the gap between face and path

The bigger the gap, the more the spin axis tilts and the more the ball bends. Two shots can start in the same place and still curve differently if their face-to-path values differ.

Strike location adds its own effect on woods. A toe strike tends to draw and a heel strike tends to fade, even when the path is neutral. So a heel-struck driver that curves right may not be a path problem at all.

Numbers on your screen that reveal a slice or hook

Each metric below answers a different question about the curve. The last column shows which kind of unit usually reports it.

Metric	What it tells you about the curve	Usually measured by
Face angle	Start direction, and whether the face was open or closed at impact	Club-data units
Club path	Whether the swing moved in-to-out or out-to-in	Club-data units
Face to path	How much the ball will curve, and which way	Club-data units; some units calculate it from face and path
Spin axis (tilt)	Which way the ball curves and how strongly	Most ball-tracking units
Side spin	Older way of expressing curve; same idea as spin axis	Many units
Offline or lateral distance	Where the ball finished left or right of the target	Most units
Impact location	Toe or heel strike that can cause gear effect	Premium camera units and some others
Attack angle	Steep, downward strikes often pair with out-to-in paths	Club-data units

Read these as a set. Face angle and path explain the cause, while spin axis and offline distance show the result. If face-to-path looks small but the ball still curves a lot, check impact location and confirm the unit's spin axis reading before changing your swing.

Measured or estimated: how each type of unit gets club data

Not every unit that shows a curve measures the club. The table groups devices by how they get club data. Maker wording on these points changes between models and software releases, so confirm the current spec sheet before you buy.

Device class	Examples	Face and path	Notes
Dual radar	Trackman 4; FlightScope X3 and X3C	Club path and face angle are reported parameters	Trackman lists a large parameter set for the Trackman 4; check the current spec for the exact count. FlightScope's X3 and X3C use Fusion Tracking, which adds a synchronised camera to the radar.
Quad or triple camera	Foresight GCQuad; Foresight GC3	Measured with club markers on some setups	Works indoors and outdoors. Confirm the GC3's club data scope with Foresight before you assume it matches the GCQuad.
Overhead camera	Uneekor EYE XO2; QED; Foresight GCHawk; Trackman iO	Club data measured from above	Some models need marked balls or club stickers. Check the maker's requirements for your model.
Camera plus radar hybrid	SkyTrak+	Dual Doppler radar reads the club; the camera reads the ball	Check the maker's listing for the exact club values it reports.
Budget radar and phone-paired	Garmin Approach R10; FlightScope Mevo+; Rapsodo MLM2Pro	Some club values may be estimated or calculated	Mevo+ offers club data through its Pro Package. Use each maker's spec sheet to see which values are direct and which are calculated.
Ball-only	Various ball-tracking units	Not reported	Shows the curve from spin axis and launch direction, but cannot separate face from path.

The further down this table you go, the more you should average several shots before drawing conclusions. A single curve from a ball-only unit can be real, but it can't tell you whether the face or the path caused it.

Read your miss with a decision tree

Work through the screen in this order. The outcomes are written for right-handers. Mirror every direction for left-handers.

Step 1: where did it start? Left, straight or right of target points mostly to the face angle.

Step 2: which way did it curve? A curve to the right means the face is open to the path. A curve to the left means the face is closed to the path.

Then match the pattern:

• Pull-slice (starts left, curves right): the face is left of target and the path is further left, out-to-in. This is the most common amateur slice.
• Push-slice (starts right, curves more right): the face is open to both the target and the path.
• Straight slice (starts at target, curves right): the face is square to target and the path is out-to-in.
• Pull-hook (starts left, curves more left): the face is closed to both the target and the path.
• Push-hook (starts right, curves left back past the target): the path is well in-to-out and the face is closed to that path.
• Straight hook (starts at target, curves left): the face is square to target and the path is in-to-out.
• Pull with little curve (starts left, finishes left): the face and path both point left of target.
• Push with little curve (starts right, finishes right): the face and path both point right of target.
• Straight (starts and finishes on target): the face and path both point at the target.

Fix the aim when the face and path point off target together. Fix the swing when the face and path point at the target but disagree with each other.

Worked example: one slice, three readings

The numbers below are illustrative. They come from no device test and are here to show the arithmetic.

Shot A. The face is 2 degrees left of target (minus 2) and the path is 7 degrees out-to-in (minus 7). Face to path is -2 minus (-7), which equals +5. The ball starts left because of the face and curves right because the gap is positive. This is a classic pull-slice.

Shot B. The face is 4 degrees open (plus 4) and the path is on target (0). Face to path is +4. The ball starts right and curves right. This is a push-slice.

Shot C. The face is square (0) and the path is 4 degrees out-to-in (minus 4). Face to path is 0 minus (-4), which equals +4. The ball starts near the target and curves right. This is a straight slice.

Shots B and C curve about the same, because both have a face-to-path gap of 4 degrees. But B needs a face fix and C needs a path fix. A ball-only unit would show them as the same shot, and club data is what tells them apart. Average at least 10 shots before acting on any single reading.

When the screen curve does not match the real ball

Run through this list before you change your swing, because a setup problem can look exactly like a swing problem.

• Unit or mat not aligned to the target line. Every shot can read as pushed or pulled. Check aligning ball, stance and unit before anything else.
• Software target not matched to your aim. Run the alignment step in the manual again.
• Mishits on budget units. Mishits can exaggerate the curve figures, so average several shots.
• Glare, dirty or scuffed balls, and other balls in view. These can cause misreads on camera units. See the lighting that causes misreads guide.
• Missing or worn club stickers or marked balls. Units that need them will misread without them.
• Short indoor flight. The ball only travels a short distance before hitting the screen, so the curve you see is calculated from spin axis and launch direction rather than observed over distance.
• Calibration out of date. Recheck the calibration and software fixes steps.

Fix misreads and calibration ↗

From numbers to a fix: a four-week practice loop

A plan keeps you from changing three things at once. Use the same club for all four weeks, and log face angle, path and face-to-path for each session.

1. Week 1: baseline. Hit 20 shots with one mid-iron. Note the average face angle, path and face-to-path, and record the start line and curve for each shot.
2. Week 2: change one thing. If path is the problem, work on it with gate or alignment-stick drills. If the face is the problem, work on grip and face control. Keep everything else constant.
3. Week 3: play under game conditions. Play a few holes in the software with realistic settings, and watch whether the average gap shrinks.
4. Week 4: confirm outdoors. Check the same numbers on the range or course, where the ball flies its full distance.

A simulator gives you feedback, but it doesn't fix a slice by itself. If the average gap won't move after several weeks of deliberate changes, a coach who can watch your swing will usually help more than extra shots on the screen. The practice plan guide sets out a structure for that kind of work, and whether a simulator improves your game covers what the screen can and can't do.

Buying for shot-shape feedback

If your main goal is curing a curve, look for three things. The first is measured face angle and club path, not just spin axis. Spin axis tells you how the ball curves, and club data tells you why. Impact location and swing video are nice to have, because they connect the numbers to what your body is doing. If you want video next to the data, a swing camera is the usual add-on.

Then check what the club data costs. Some units include it, while others sell it as an upgrade or subscription. Examples include the Mevo+ Pro Package, the Bushnell Launch Pro club data upgrade and SkyTrak plans. Pricing and terms change, so check current listings before you assume a number.

Your skill level also shapes how precise the readings need to be. How much accuracy you need at each skill level can help you decide how much to spend. For a shortlist, start with launch monitors that measure club data, then compare radar and camera tracking and the most accurate launch monitors. If you want to understand where the numbers come from in the first place, how launch monitors measure a shot is the place to start.

Compare launch monitors with club data ↗

Slice and hook questions from simulator owners

Why does the simulator show a slice when my outdoor shots fly straight?

Usually it's alignment. If the unit, mat or software target is not lined up with where you aim, every shot can read as pushed or pulled. Check ball condition, lighting and calibration next. Outdoor shots also have wind and lie effects that can hide a slight fade, so compare averages over several shots rather than single results. The calibration and software fixes page walks through the checks.

Can a launch monitor tell a fade from a slice?

Physically they are the same mechanism, and the difference is size. Use face to path and offline distance together. A small, repeatable gap that finishes near the target is a fade. A large gap that finishes well offline is a slice. Set your own threshold for each club, since what counts as a large gap can differ from one club to the next.

Does an off-centre strike change what the screen reports?

Yes. With woods, gear effect means a toe strike tends to draw and a heel strike tends to fade, even when the path is neutral. Units that measure impact location help you separate a strike problem from a swing-path problem. If the curve changes with where the ball hits the face but not with your path, the fix is in contact, not in your swing plane. Check whether your unit reports impact location before you rely on that split.

Is spin axis or side spin the better number to watch?

They describe the same curve in two ways. Spin axis, the tilt in degrees, is the modern standard because the curve depends on the tilt and the total spin together. Side spin in rpm is the older expression, and many units still show it. If your unit shows both, use spin axis as the main curve number and treat side spin as a secondary check. Read each maker's definitions, since labels differ between brands.

Do left-handed golfers need different settings to read curve?

Set your handedness in the software and the directions mirror, so a left-hander's slice curves left. Camera units mounted on one side of the ball may need to move to the other side, while radar placed behind the golfer often doesn't. Check the maker's placement guide for your model. For setups built around handedness, see simulators for left and right-handed use.